/*
 * Copyright 2010-2025 Hyland Software, Inc. and its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.activiti.engine.impl.util;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
import org.activiti.engine.ActivitiIllegalArgumentException;

/**
 * helper/convenience methods for working with collections.
 *
 */
public class CollectionUtil {

    // No need to instantiate
    private CollectionUtil() {}

    /**
     * Helper method that creates a singleton map.
     *
     * Alternative for singletonMap()), since that method returns a generic typed map <K,T> depending on the input type, but we often need a <String, Object> map.
     */
    public static Map<String, Object> singletonMap(String key, Object value) {
        Map<String, Object> map = new HashMap<>();
        map.put(key, value);
        return map;
    }

    /**
     * Helper method to easily create a map with keys of type String and values of type Object. Null values are allowed.
     *
     * @param objects varargs containing the key1, value1, key2, value2, etc. Note: although an Object, we will cast the key to String internally
     * @throws ActivitiIllegalArgumentException when objects are not even or key/value are not expected types
     */
    public static Map<String, Object> map(Object... objects) {
        return mapOfClass(Object.class, objects);
    }

    /**
     * Helper method to easily create a map with keys of type String and values of a given Class. Null values are allowed.
     *
     * @param clazz the target Value class
     * @param objects varargs containing the key1, value1, key2, value2, etc. Note: although an Object, we will cast the key to String internally
     * @throws ActivitiIllegalArgumentException when objects are not even or key/value are not expected types
     */
    public static <T> Map<String, T> mapOfClass(Class<T> clazz, Object... objects) {
        if (objects.length % 2 != 0) {
            throw new ActivitiIllegalArgumentException(
                "The input should always be even since we expect a list of key-value pairs!"
            );
        }

        Map<String, T> map = new HashMap();
        for (int i = 0; i < objects.length; i += 2) {
            int keyIndex = i;
            int valueIndex = i + 1;
            Object key = objects[keyIndex];
            Object value = objects[valueIndex];
            if (!String.class.isInstance(key)) {
                throw new ActivitiIllegalArgumentException(
                    "key at index " + keyIndex + " should be a String but is a " + key.getClass()
                );
            }
            if (value != null && !clazz.isInstance(value)) {
                throw new ActivitiIllegalArgumentException(
                    "value at index " + valueIndex + " should be a " + clazz + " but is a " + value.getClass()
                );
            }
            map.put((String) key, (T) value);
        }

        return map;
    }

    public static boolean isEmpty(Collection<?> collection) {
        return (collection == null || collection.isEmpty());
    }

    public static boolean isNotEmpty(Collection<?> collection) {
        return !isEmpty(collection);
    }
}
